Of course, there are dozens of Bond cars floating around out there in collections, but none as unique as this Lotus, which ended a chase scene in the movie by taking a long walk off a short pier and transforming itself into a submersible. Since CGI was a meaningless collection of letters back then, the producers of the film actually built a fully functional Lotus Esprit submarine for the shoot. They hired Perry Oceangraphic in Florida to turn one of their six Esprit body shells into a fully functioning submarine, and former US Navy Seal Don Griffin was tapped for piloting duties. RM Auctions claims the Esprit submarine cost over $100,000 to build at the time, which is about $400,000 in today’s dollars.

The submarine car comes with a incredible story, too. After filming in the ’70s, it was shipped to Long Island, NY where it was kept in a storage unit that was paid in advance for ten years. When the storage contract ended in 1989 and no one claimed the contents, they were sold off in a blind auction to an area couple who had no idea what they were getting. The car has been shown occasionally in the years since, but its value remained purely speculative, until now. To date, the most valuable Bond car we know of is the original Aston Martin DB5 used in Goldfinger and Thunderball that sold for $4.6 million in 2010, but when the gavel falls at RM Auctions’ London sale in September, we’ll find out if the car nicknamed “Wet Nellie” on set can beat it.

Check out the car in its current condition in the gallery above, and scroll down to watch the underwater scene that made it famous.